This is a request for an extension of the training program in Environmental Health Statistics at the Harvard School of Public Health (HSPH). The program prepares pre-doctoral and postdoctoral fellows for research in the application of biostatistics, statistical genetics and genomics to environmental health. Administered through the Department of Biostatistics, the program features active participation by faculty members from the HSPH Departments of Environmental Health and Department of Epidemiology. Trainees will receive high-quality instruction in basic biostatistical models, such as probability, statistical inference, computing, and data analysis. The program also provides training in specialized topics of particular relevance for environmental applications, such as longitudinal and multivariate data analysis, causal inference, and missing data techniques, as well as statistical genetics, environmental genomics and other high-dimensional data techniques. In addition, the program provides training in statistical methods relevant to environmental exposure assessment such as measurement error models, spatial statistics, and data fusion methods for integrating exposure and health data from disparate temporal and spatial scales. Training includes applied course work in environmental health, a regular Environmental Statistics Seminar Series in which faculty, students, and fellows present their own environmental health-related research, and annual symposia. An important focus of training will be the opportunity to collaborate with faculty members from all three participating departments on biostatistical research as it applies to environmental health. All trainees will participate in Harvard's program on scientific integrityin the conduct of research, research workshops focusing on grantsmanship skills and project management, and formal, hands-on training in strategies for effective interdisciplinary collaboration. Since its inception in 1982, this training program has emphasized strong links to the environmental sciences. In recent years, program trainers have placed particular importance on the recruitment of students from underrepresented minority groups. The focus on interdisciplinary training at the Harvard School of Public Health, its rich research resources, and its talented and diverse student body and faculty makes it an ideal setting in which to provide a training program in environmental statistics.